Python rootoftools.rootof函数代码示例

def test_CRootOf___eval_Eq__():
    f = Function('f')
    eq = x**3 + x + 3
    r = rootof(eq, 2)
    r1 = rootof(eq, 1)
    assert Eq(r, r1) is S.false
    assert Eq(r, r) is S.true
    assert Eq(r, x) is S.false
    assert Eq(r, 0) is S.false
    assert Eq(r, S.Infinity) is S.false
    assert Eq(r, I) is S.false
    assert Eq(r, f(0)) is S.false
    assert Eq(r, f(0)) is S.false
    sol = solve(eq)
    for s in sol:
        if s.is_real:
            assert Eq(r, s) is S.false
    r = rootof(eq, 0)
    for s in sol:
        if s.is_real:
            assert Eq(r, s) is S.true
    eq = x**3 + x + 1
    sol = solve(eq)
    assert [Eq(rootof(eq, i), j) for i in range(3) for j in sol] == [
        False, False, True, False, True, False, True, False, False]
    assert Eq(rootof(eq, 0), 1 + S.ImaginaryUnit) == False

def test_CRootOf_evalf_caching_bug():
    r = rootof(x**5 - 5*x + 12, 1)
    r.n()
    a = r._get_interval()
    r = rootof(x**5 - 5*x + 12, 1)
    r.n()
    b = r._get_interval()
    assert a == b

def test_CRootOf_attributes():
    r = rootof(x**3 + x + 3, 0)
    assert r.is_number
    assert r.free_symbols == set()
    # if the following assertion fails then multivariate polynomials
    # are apparently supported and the RootOf.free_symbols routine
    # should be changed to return whatever symbols would not be
    # the PurePoly dummy symbol
    raises(NotImplementedError, lambda: rootof(Poly(x**3 + y*x + 1, x), 0))

def test_solve_univariate_inequality():
    assert isolve(x**2 >= 4, x, relational=False) == Union(Interval(-oo, -2),
        Interval(2, oo))
    assert isolve(x**2 >= 4, x) == Or(And(Le(2, x), Lt(x, oo)), And(Le(x, -2),
        Lt(-oo, x)))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x, relational=False) == \
        Union(Interval(1, 2), Interval(3, oo))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x) == \
        Or(And(Le(1, x), Le(x, 2)), And(Le(3, x), Lt(x, oo)))
    assert isolve((x - 1)*(x - 2)*(x - 4) < 0, x, domain = FiniteSet(0, 3)) == \
        Or(Eq(x, 0), Eq(x, 3))
    # issue 2785:
    assert isolve(x**3 - 2*x - 1 > 0, x, relational=False) == \
        Union(Interval(-1, -sqrt(5)/2 + S(1)/2, True, True),
              Interval(S(1)/2 + sqrt(5)/2, oo, True, True))
    # issue 2794:
    assert isolve(x**3 - x**2 + x - 1 > 0, x, relational=False) == \
        Interval(1, oo, True)
    #issue 13105
    assert isolve((x + I)*(x + 2*I) < 0, x) == Eq(x, 0)
    assert isolve(((x - 1)*(x - 2) + I)*((x - 1)*(x - 2) + 2*I) < 0, x) == Or(Eq(x, 1), Eq(x, 2))
    assert isolve((((x - 1)*(x - 2) + I)*((x - 1)*(x - 2) + 2*I))/(x - 2) > 0, x) == Eq(x, 1)
    raises (ValueError, lambda: isolve((x**2 - 3*x*I + 2)/x < 0, x))

    # numerical testing in valid() is needed
    assert isolve(x**7 - x - 2 > 0, x) == \
        And(rootof(x**7 - x - 2, 0) < x, x < oo)

    # handle numerator and denominator; although these would be handled as
    # rational inequalities, these test confirm that the right thing is done
    # when the domain is EX (e.g. when 2 is replaced with sqrt(2))
    assert isolve(1/(x - 2) > 0, x) == And(S(2) < x, x < oo)
    den = ((x - 1)*(x - 2)).expand()
    assert isolve((x - 1)/den <= 0, x) == \
        Or(And(-oo < x, x < 1), And(S(1) < x, x < 2))

    n = Dummy('n')
    raises(NotImplementedError, lambda: isolve(Abs(x) <= n, x, relational=False))
    c1 = Dummy("c1", positive=True)
    raises(NotImplementedError, lambda: isolve(n/c1 < 0, c1))
    n = Dummy('n', negative=True)
    assert isolve(n/c1 > -2, c1) == (-n/2 < c1)
    assert isolve(n/c1 < 0, c1) == True
    assert isolve(n/c1 > 0, c1) == False

    zero = cos(1)**2 + sin(1)**2 - 1
    raises(NotImplementedError, lambda: isolve(x**2 < zero, x))
    raises(NotImplementedError, lambda: isolve(
        x**2 < zero*I, x))
    raises(NotImplementedError, lambda: isolve(1/(x - y) < 2, x))
    raises(NotImplementedError, lambda: isolve(1/(x - y) < 0, x))
    raises(TypeError, lambda: isolve(x - I < 0, x))

    zero = x**2 + x - x*(x + 1)
    assert isolve(zero < 0, x, relational=False) is S.EmptySet
    assert isolve(zero <= 0, x, relational=False) is S.Reals

    # make sure iter_solutions gets a default value
    raises(NotImplementedError, lambda: isolve(
        Eq(cos(x)**2 + sin(x)**2, 1), x))

def test_solve_univariate_inequality():
    assert isolve(x**2 >= 4, x, relational=False) == Union(Interval(-oo, -2),
        Interval(2, oo))
    assert isolve(x**2 >= 4, x) == Or(And(Le(2, x), Lt(x, oo)), And(Le(x, -2),
        Lt(-oo, x)))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x, relational=False) == \
        Union(Interval(1, 2), Interval(3, oo))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x) == \
        Or(And(Le(1, x), Le(x, 2)), And(Le(3, x), Lt(x, oo)))
    # issue 2785:
    assert isolve(x**3 - 2*x - 1 > 0, x, relational=False) == \
        Union(Interval(-1, -sqrt(5)/2 + S(1)/2, True, True),
              Interval(S(1)/2 + sqrt(5)/2, oo, True, True))
    # issue 2794:
    assert isolve(x**3 - x**2 + x - 1 > 0, x, relational=False) == \
        Interval(1, oo, True)

    # numerical testing in valid() is needed
    assert isolve(x**7 - x - 2 > 0, x) == \
        And(rootof(x**7 - x - 2, 0) < x, x < oo)

    # handle numerator and denominator; although these would be handled as
    # rational inequalities, these test confirm that the right thing is done
    # when the domain is EX (e.g. when 2 is replaced with sqrt(2))
    assert isolve(1/(x - 2) > 0, x) == And(S(2) < x, x < oo)
    den = ((x - 1)*(x - 2)).expand()
    assert isolve((x - 1)/den <= 0, x) == \
        Or(And(-oo < x, x < 1), And(S(1) < x, x < 2))

    n = Dummy('n')
    raises(NotImplementedError, lambda: isolve(Abs(x) <= n, x, relational=False))

def test_solve_univariate_inequality():
    assert isolve(x**2 >= 4, x, relational=False) == Union(Interval(-oo, -2),
        Interval(2, oo))
    assert isolve(x**2 >= 4, x) == Or(And(Le(2, x), Lt(x, oo)), And(Le(x, -2),
        Lt(-oo, x)))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x, relational=False) == \
        Union(Interval(1, 2), Interval(3, oo))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x) == \
        Or(And(Le(1, x), Le(x, 2)), And(Le(3, x), Lt(x, oo)))
    # issue 2785:
    assert isolve(x**3 - 2*x - 1 > 0, x, relational=False) == \
        Union(Interval(-1, -sqrt(5)/2 + S(1)/2, True, True),
              Interval(S(1)/2 + sqrt(5)/2, oo, True, True))
    # issue 2794:
    assert isolve(x**3 - x**2 + x - 1 > 0, x, relational=False) == \
        Interval(1, oo, True)

    # XXX should be limited in domain, e.g. between 0 and 2*pi
    assert isolve(sin(x) < S.Half, x) == \
        Or(And(-oo < x, x < pi/6), And(5*pi/6 < x, x < oo))
    assert isolve(sin(x) > S.Half, x) == And(pi/6 < x, x < 5*pi/6)

    # numerical testing in valid() is needed
    assert isolve(x**7 - x - 2 > 0, x) == \
        And(rootof(x**7 - x - 2, 0) < x, x < oo)

    # handle numerator and denominator; although these would be handled as
    # rational inequalities, these test confirm that the right thing is done
    # when the domain is EX (e.g. when 2 is replaced with sqrt(2))
    assert isolve(1/(x - 2) > 0, x) == And(S(2) < x, x < oo)
    den = ((x - 1)*(x - 2)).expand()
    assert isolve((x - 1)/den <= 0, x) == \
        Or(And(-oo < x, x < 1), And(S(1) < x, x < 2))

def test_nfloat():
    from sympy.core.basic import _aresame
    from sympy.polys.rootoftools import rootof

    x = Symbol("x")
    eq = x**(S(4)/3) + 4*x**(S(1)/3)/3
    assert _aresame(nfloat(eq), x**(S(4)/3) + (4.0/3)*x**(S(1)/3))
    assert _aresame(nfloat(eq, exponent=True), x**(4.0/3) + (4.0/3)*x**(1.0/3))
    eq = x**(S(4)/3) + 4*x**(x/3)/3
    assert _aresame(nfloat(eq), x**(S(4)/3) + (4.0/3)*x**(x/3))
    big = 12345678901234567890
    # specify precision to match value used in nfloat
    Float_big = Float(big, 15)
    assert _aresame(nfloat(big), Float_big)
    assert _aresame(nfloat(big*x), Float_big*x)
    assert _aresame(nfloat(x**big, exponent=True), x**Float_big)
    assert nfloat({x: sqrt(2)}) == {x: nfloat(sqrt(2))}
    assert nfloat({sqrt(2): x}) == {sqrt(2): x}
    assert nfloat(cos(x + sqrt(2))) == cos(x + nfloat(sqrt(2)))

    # issue 6342
    f = S('x*lamda + lamda**3*(x/2 + 1/2) + lamda**2 + 1/4')
    assert not any(a.free_symbols for a in solveset(f.subs(x, -0.139)))

    # issue 6632
    assert nfloat(-100000*sqrt(2500000001) + 5000000001) == \
        9.99999999800000e-11

    # issue 7122
    eq = cos(3*x**4 + y)*rootof(x**5 + 3*x**3 + 1, 0)
    assert str(nfloat(eq, exponent=False, n=1)) == '-0.7*cos(3.0*x**4 + y)'

def test_issue_8235():
    assert reduce_inequalities(x**2 - 1 < 0) == \
        And(S(-1) < x, x < S(1))
    assert reduce_inequalities(x**2 - 1 <= 0) == \
        And(S(-1) <= x, x <= 1)
    assert reduce_inequalities(x**2 - 1 > 0) == \
        Or(And(-oo < x, x < -1), And(x < oo, S(1) < x))
    assert reduce_inequalities(x**2 - 1 >= 0) == \
        Or(And(-oo < x, x <= S(-1)), And(S(1) <= x, x < oo))

    eq = x**8 + x - 9  # we want CRootOf solns here
    sol = solve(eq >= 0)
    tru = Or(And(rootof(eq, 1) <= x, x < oo), And(-oo < x, x <= rootof(eq, 0)))
    assert sol == tru

    # recast vanilla as real
    assert solve(sqrt((-x + 1)**2) < 1) == And(S(0) < x, x < 2)

def test_CRootOf_all_roots():
    assert Poly(x**5 + x + 1).all_roots() == [
        rootof(x**3 - x**2 + 1, 0),
        -S(1)/2 - sqrt(3)*I/2,
        -S(1)/2 + sqrt(3)*I/2,
        rootof(x**3 - x**2 + 1, 1),
        rootof(x**3 - x**2 + 1, 2),
    ]

    assert Poly(x**5 + x + 1).all_roots(radicals=False) == [
        rootof(x**3 - x**2 + 1, 0),
        rootof(x**2 + x + 1, 0, radicals=False),
        rootof(x**2 + x + 1, 1, radicals=False),
        rootof(x**3 - x**2 + 1, 1),
        rootof(x**3 - x**2 + 1, 2),
    ]

def test_CRootOf_subs():
    assert rootof(x**3 + x + 1, 0).subs(x, y) == rootof(y**3 + y + 1, 0)

def test_is_disjoint():
    eq = x**3 + 5*x + 1
    ir = rootof(eq, 0)._get_interval()
    ii = rootof(eq, 1)._get_interval()
    assert ir.is_disjoint(ii)
    assert ii.is_disjoint(ir)

def test_issue_7876():
    l1 = Poly(x**6 - x + 1, x).all_roots()
    l2 = [rootof(x**6 - x + 1, i) for i in range(6)]
    assert frozenset(l1) == frozenset(l2)

def test_CRootOf_real_roots():
    assert Poly(x**5 + x + 1).real_roots() == [rootof(x**3 - x**2 + 1, 0)]
    assert Poly(x**5 + x + 1).real_roots(radicals=False) == [rootof(
        x**3 - x**2 + 1, 0)]

def test_CRootOf___eq__():
    assert (rootof(x**3 + x + 3, 0) == rootof(x**3 + x + 3, 0)) is True
    assert (rootof(x**3 + x + 3, 0) == rootof(x**3 + x + 3, 1)) is False
    assert (rootof(x**3 + x + 3, 1) == rootof(x**3 + x + 3, 1)) is True
    assert (rootof(x**3 + x + 3, 1) == rootof(x**3 + x + 3, 2)) is False
    assert (rootof(x**3 + x + 3, 2) == rootof(x**3 + x + 3, 2)) is True

    assert (rootof(x**3 + x + 3, 0) == rootof(y**3 + y + 3, 0)) is True
    assert (rootof(x**3 + x + 3, 0) == rootof(y**3 + y + 3, 1)) is False
    assert (rootof(x**3 + x + 3, 1) == rootof(y**3 + y + 3, 1)) is True
    assert (rootof(x**3 + x + 3, 1) == rootof(y**3 + y + 3, 2)) is False
    assert (rootof(x**3 + x + 3, 2) == rootof(y**3 + y + 3, 2)) is True

def test_CRootOf___new__():
    assert rootof(x, 0) == 0
    assert rootof(x, -1) == 0

    assert rootof(x, S.Zero) == 0

    assert rootof(x - 1, 0) == 1
    assert rootof(x - 1, -1) == 1

    assert rootof(x + 1, 0) == -1
    assert rootof(x + 1, -1) == -1

    assert rootof(x**2 + 2*x + 3, 0) == -1 - I*sqrt(2)
    assert rootof(x**2 + 2*x + 3, 1) == -1 + I*sqrt(2)
    assert rootof(x**2 + 2*x + 3, -1) == -1 + I*sqrt(2)
    assert rootof(x**2 + 2*x + 3, -2) == -1 - I*sqrt(2)

    r = rootof(x**2 + 2*x + 3, 0, radicals=False)
    assert isinstance(r, RootOf) is True

    r = rootof(x**2 + 2*x + 3, 1, radicals=False)
    assert isinstance(r, RootOf) is True

    r = rootof(x**2 + 2*x + 3, -1, radicals=False)
    assert isinstance(r, RootOf) is True

    r = rootof(x**2 + 2*x + 3, -2, radicals=False)
    assert isinstance(r, RootOf) is True

    assert rootof((x - 1)*(x + 1), 0, radicals=False) == -1
    assert rootof((x - 1)*(x + 1), 1, radicals=False) == 1
    assert rootof((x - 1)*(x + 1), -1, radicals=False) == 1
    assert rootof((x - 1)*(x + 1), -2, radicals=False) == -1

    assert rootof((x - 1)*(x + 1), 0, radicals=True) == -1
    assert rootof((x - 1)*(x + 1), 1, radicals=True) == 1
    assert rootof((x - 1)*(x + 1), -1, radicals=True) == 1
    assert rootof((x - 1)*(x + 1), -2, radicals=True) == -1

    assert rootof((x - 1)*(x**3 + x + 3), 0) == rootof(x**3 + x + 3, 0)
    assert rootof((x - 1)*(x**3 + x + 3), 1) == 1
    assert rootof((x - 1)*(x**3 + x + 3), 2) == rootof(x**3 + x + 3, 1)
    assert rootof((x - 1)*(x**3 + x + 3), 3) == rootof(x**3 + x + 3, 2)
    assert rootof((x - 1)*(x**3 + x + 3), -1) == rootof(x**3 + x + 3, 2)
    assert rootof((x - 1)*(x**3 + x + 3), -2) == rootof(x**3 + x + 3, 1)
    assert rootof((x - 1)*(x**3 + x + 3), -3) == 1
    assert rootof((x - 1)*(x**3 + x + 3), -4) == rootof(x**3 + x + 3, 0)

    assert rootof(x**4 + 3*x**3, 0) == -3
    assert rootof(x**4 + 3*x**3, 1) == 0
    assert rootof(x**4 + 3*x**3, 2) == 0
    assert rootof(x**4 + 3*x**3, 3) == 0

    raises(GeneratorsNeeded, lambda: rootof(0, 0))
    raises(GeneratorsNeeded, lambda: rootof(1, 0))

    raises(PolynomialError, lambda: rootof(Poly(0, x), 0))
    raises(PolynomialError, lambda: rootof(Poly(1, x), 0))
    raises(PolynomialError, lambda: rootof(x - y, 0))
    # issue 8617
    raises(PolynomialError, lambda: rootof(exp(x), 0))

    raises(NotImplementedError, lambda: rootof(x**3 - x + sqrt(2), 0))
    raises(NotImplementedError, lambda: rootof(x**3 - x + I, 0))

    raises(IndexError, lambda: rootof(x**2 - 1, -4))
    raises(IndexError, lambda: rootof(x**2 - 1, -3))
    raises(IndexError, lambda: rootof(x**2 - 1, 2))
    raises(IndexError, lambda: rootof(x**2 - 1, 3))
    raises(ValueError, lambda: rootof(x**2 - 1, x))

    assert rootof(Poly(x - y, x), 0) == y

    assert rootof(Poly(x**2 - y, x), 0) == -sqrt(y)
    assert rootof(Poly(x**2 - y, x), 1) == sqrt(y)

    assert rootof(Poly(x**3 - y, x), 0) == y**Rational(1, 3)

    assert rootof(y*x**3 + y*x + 2*y, x, 0) == -1
    raises(NotImplementedError, lambda: rootof(x**3 + x + 2*y, x, 0))

    assert rootof(x**3 + x + 1, 0).is_commutative is True